<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript">
			var a=3;
			a++;    /*a+=1;     a=a+1    自增  */
			console.log(a);

/*后加,先计算运算，再计算++*/
			var b=2;
			var c=3;
			var d=b++ + c++;       /*var d=b+c; b=b+1;  c=c+1;*/
			console.log(b);        /*3*/
			console.log(c);        /*4*/
			console.log(d);        /*5*/
			
/*先加，先计算++，再计算运算*/			
			var e=2;
			var f=3;
			var g=++e + ++f;       /*var e=e+1;  f=f+1;  g=e+f;*/
			console.log(e);        /*3*/
			console.log(f);        /*4*/
			console.log(g);        /*7*/
		</script>
	</head>
	<body>
	</body>
</html>
